Electric motor control system



Aug. 23, 1949. R. D. GAMBRILL ELECTRIC MOTOR CONTROL SYSTEM 3 Sheets-Sheet 1 Filed Jan. 17, 1946 lNl/EA/TOR R0. GA MBR/LL By .47..

FIG.

ATTORNEY g- R. D. GAMBRILL 2,479,920

ELECTRIC MOTOR CONTROL SYSTEM Filed Jan. 17, 1946 3 SheetsSheet 2 f & ill L El III [:1 [1| 1:! [:I III 1:! III III Ill g sum G m\ 1 Vl EN 70/? R 0. GAMER/LL BMW A T TOH/VEV 1949- R. D. GAMBRILL 2,479,920

ELECTRIC MOTOR CONTROL -YSTEM Filed Jan. 17, 1946 5 Sheets-Sheet 5 lNVEA/TO F/GJ. R 0 GAMER/LL TTOR/VEV Patented Aug. 23, 1949 ELECTRIC MOTOR CONTROL SYSTEM Richard D. Gambrill, Baltimore, Md., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January 17, 1946, Serial No. 641,848

1 Claim. 1

This invention relates to electric motor control systems, and more particularly to electric control systemsfor use with apparatus for testing cable splices.

In the manufacture of multi-conductor electric cables, it is often necessary to splice normally manufactured lengths of cable together in order to form a cable whose length conforms to specific manufacturing specifications or is suitable for a particular field installation in which the cable is to be used. Cable splices are also necessitated by the fact that when insulation faults are detected in such cables -the faulty portion must be removed from the cable and the ends thereof spliced together.

Various types of splices are employed in joining two lengths of cable, however, the present invention is related to the testing of a. particular type which is formed by butting the ends of the individual conductors of the cable and causing a small amount of silver solder, or the like, to flow around the joint and join the ends thereof together. When the splice is completed, it is usually subjected to certain mechanical and electrical tests to determine whether the splice has been made properly and whether it will remain intact during normal handling in the field. The mechanical testing of such cable splices comprises flexing the splice while it is under tension, whereby substantial stresses are applied to the welded joints of the splice. If the welded joints are improperly formed they will break apart during the flexing test, which fact may be determined by having a simple continuity test set connected to the ends of the spliced cable during the flexing test.

An object of the invention is to provide new and improved electric motor control systems.

In accordance with a specific embodiment of the invention there is provided a continuity testing circuit comprising a plurality of indicating means connected in series with the individual conductors of a multi-conductor cable and a flexing drive motor control circuit comprising means for energizing the motor and means for deenergizing the motor after a predetermined number of cycles.

A clear understanding of the invention will be had from the following detailed description of a preferred embodiment thereof, when read in conjunction with the appended drawing, in which Fig. 1 is a side elevation of a cable splice flexing apparatus which may be used in connection with the electric motor control circuit embodying the invention;

2 Fig. 2 is a fragmentary end elevation of a portion of the driving mechanism shown in Fig. 1 as seen from the right hand side of that figure;

Fig. 3 is an enlarged horizontal sectional view of a portion of the apparatus taken along the Fig. 3, and ll) Fig. 5 is a schematic wiring diagram showing a spliced cable connected to a continuity indicating circuit and a control circuit employed to automatically control the motor driving the flex- ,ing apparatus shown in Fig. 1.

,thereon and serves to drive a sprocket I! by means of a roller chain [8.

the column 21.

The sprocket I1 is keyed to a crank shaft l9 which is rotatably mounted in a pair of bearings 2020 which are rigidly secured to the plate I I. The crank shaft l9 has a crank 2| keyed on one end thereof, the other end of which is provided with a crank pin 22. A connecting rod 23 has one end thereof rotatably positioned on the crank pin 22. The other end of the connecting rod 23 is rotatably secured to a crosshead pin 24 mounted on a crosshead 25 which is slidably positioned in a slide 26. column 21, which is mounted in an upright position ori the plate ll adjacent to the bench l2. The slide 26 is so positioned on the column 21 that, when the crank 21 is in the full line position shown on the drawing, the crosshead 25 is raised to the upper end of the slide 26 by the connecting rod 23. When the crank 2| is rotated to the broken line position shown on the drawing, the connecting rod 23 carries the crosshead 25 to the lower end of the slide 26.

A grooved pulley 28 is rotatably positioned on a shaft 30 rigidly mounted on the upper end of The diameter of the pulley 28 is such that the center line of the groove therein is substantially in line with the center line of the crosshead 25 and the slide 26.

A suitable cable grip, such as a cable grip .3! (Figs. 3 and 4), is rigidly secured to the crosshead 25. The grip 3| is substantially identical The slide 26 is rigidly secured to a with the one described and claimed in copending application Serial No. 529,518, filed April 4, 1944 by O. G. Nelson.

The cable grip 3! (Figs. 3 and 4) comprises a stationary block 32 and a movable block 33, each of which has a semicircular opening 34 provided on one face thereof and extending the entire length or" the block, said openings 34-34 being provided with a plurality of semi c rc'ular serrations 35-35 (Fig. 4). The semicircular openings 34-34 have rubber inserts 36-35 moulded therein whereby the serrations 35-35 serve to firmly secure the inserts 35-36 in the openings 34-34. Each of the rubber inserts 36-35 has a semicircular groove}?! moulded therein and extending the entire length of the insert 36. The blocks 32 and 33 have slots 38- 38 milled in each side thereof for the full depth of the block, and a plurality of bores 39-39 drilled therein which connect with the slots The blocks 32 and 33 are assembled as shown in Fig. 3, so that the inserts 35-35 are adiacent to each other. whereby the semicircular grooves 31-31 therein are aligned to form a split bore therethrough. The stationary block '32 is rigidly secured to the crosshead 25 and has the movable block 33 hingedly attached thereto by means of a link 49 slidably positioned in the left hand slots 38-38 and .rotatably positioned therein by a pair of rods 44- 3! mova-bly positioned in the left hand bores 39-39. The hinged block 33 is maintained in its closed position (Fig. 3) by means of a link 42 slidably positioned in the right hand slots 38-38 and has one end thereof rotatably mounted on a rod 4-3 positioned in the right hand bore 39 of the stationary block 32. The opposite end 44 of the link 42 is circular in cross=section and is threaded to receive a tightenlng lever 45. When the movable block 33 is maintained in its closed position (Fig. 3) with respect to the stationary block 32, the semicircular grooves 31-3! of the rubber inserts 33-35 form a split bore whose diameter is adjustable by means or the tightening lever '45.

There is also positioned on the plate H a hollow, sheet steel guide '46 of rectangular crosssection, in which a weight '41 is slidably positinned. The weight '4! is provided with a steel bracket 48 on its upper end to which a cable grip E9 is secured. The cable grip 43 is identical with the cable grip 3! secured to the crosshead 25 and described herein'above.

a weightliftin mechanism so also is mounted on the plate H and comprises a treadle arm rotatably mounted on a bearing 52 by means oi a pin 53 positioned in the bearing 52. The treadle arm 5'! extends beyond the bearing 52 into the weight guide 45 and has ap'ad 54 movably positioned on the end thereof. A spring 56 is posi tioned between the treadle arm 5! and the plate II in order to maintain the weight lifting mechanism 50 in its normal position.

The Weight lifting mechanism 53 is designed to be actuated by the foot of an operator and Serves to lift the ht a substantial distance abbve the p -form so that when the crosshead 25 T5311 its pp st position as shown on the drawing, the weight 41 may be clamped t the left haf'lfl P ti-On of aspliced cable 65 looped Over rooved pulley 2s and having a portion of its right hand side clamped in the cable grip 3| secured on "the crosshead '25. The spliced an $9 is made p of two lengths of multi-co 4 ductor' cables BI and 62, which are joined together by a splice 53.

The spliced cable 60 is looped over the pulley 28 (Fig. 1) so that the upper end of the splice 63 formed therein engages the left hand side of th pulley 28 when the crosshead 25 is in its uppermost position on the slide 26. When the crosshead 25 is moved to its lowermost position, the Splice 63 will be drawn around the peri her of the pulley 28 and assume a position on the right hand side of the pulley '28 shown in the broken lines on the drawing (Fig. 1). In other words, each time the crosshead 25 moves from its uppermost position to its lowermost position or vice versa, the splice 63 of the cable 60 is drawn around the periphery of the pulley 28 whereby the splice 63 is bent around the pulley 2-3 approximately 180. This flexing or bending of the splice 63 tends to fracture or break open improperly welded joints of the conductors of the spliced cable 63.

' A ring it is adjustably positioned on the hub of the sprocket ii and has threadedly mounted therein a round headed bolt 16. The ring 15 and the bolt 16 secured thereon are orientated with the erosshead '25 "so that, when the motor i3 is deenerg'i'z'ed after a given flexing operation oi the splice '63, the crosshead 2'5 always comes to rest at approximately the u per end of the slide as. A 'supersen'sitive switch on is mounted on a bracket '81 secured to one of the bearings zt-zt, and has an operatin arm 82 aligned with the ring 15 and the bolt It carried thereby. When the sprocket I1 is rotated, the rin 15 secured on the hub thereof is rotated, whereupon the head of the bolt 15 mounted thereon strikes the arm 82 of the supersensitive switch 80.

There ispositioned on the top of the bench 12 a test set 85, which contains the electrical apparatus used to automatically control the operation of the motor 13 which drives the flexin apparatus shown in Fig. 1. A pair of leads '8'6-86 extend from the test set 85 and have a pair of connectors 81-81 provided on their ends, which are rigidly secured to an angular support B8 mounted on the bench !2 adjacent to the test set 85. -A pair of connectors BQ-BUprovided on the ends of the cable 60 are similar to the connectbrs Sl-B! but are of the opposite hand thereto so that they may be inserted into the connectors 81-87 of the test set leads lit-3t. The test set 85 is provided with a control panel on which is positioned a plurality of indicating lamps 91-91, a push button 92 associated with the indicting lamps, a start push button 93 and a stop push button 94.

The cable splice flexing apparatus shown in Fig. 1 is described and claimed specifically in copending application Serial No. 641,849, filed January 17, 1946, by E. Lewis.

The apparatus contained in the test set 85 is shown in schematic form in Fig. 5 of the drawings, wherein a pair of volt A. C. control busses I09 and IUI serve to supply potential to the continuity indicating circuit, and the motor control circuit.

As is shown in Fig. 5, the push button 92 is connected across the control buses I33 and H3! at junctions I03 and HM, respectively, and has connected in series therewith a primary winding "15 of a potential transformer I06. A secondary winding 101 of the transformer Hi6 has one side thereof connected directly to a plurality of individual conductors "3-! l3 of the multi-conduc-, tor cable Bl of the spliced cable '60. The multiposite sides connected to a plurality of conduc tors III--III of the multi-conductor cable 62 which is identical in construction with the cable 6|. The spliced cable 60 contains the splice 63 in which the conductors III-III of the cable BI and the conductors I I3II3 of the cable 62 have been butt-welded by means of silver'solder, or the like, and the respective joints have thereafter been individually insulated and enclosed in a braided metallic sleeve over which is placed an outer insulating jacket made of a material similar to that used in the jacket H2 of the cable 6|.

When the pushbutton 92 is closed; the potential transformer I06 is energized, whereuponthe individual parallel circuits comprising the indicating lamps 9I-0I, the conductors III-I II and I I3-I I3 have impressed thereacross a potential sufiicient to cause the indicating lamps I-3I to glow, providing there are no breaks or defects in the joints between the individual conductors within the splice 63.

A normally open contact II5 (Fig. 5) of the start-push button 93 has one side thereof connected to a junction I I6 on the bus I00 and the other side thereof connected to a normally closed contact of the stop-push button 94, which is in turn connected to a normally closed contact I of a control relay I2I, The other side of the normally closed contact I20 is connected to an operating coil I22 of a magnetic relay I23 and has its other side connected directly to the control bus IOI at a junction I24. A normally closed contact I25 of the push button 93 has one side thereof connected to a junction I26 on the control bus I00 and has its other side thereof connected directly to a normally open contact I21 on the relay Ill. The other side of the contact I21 is connected to a junction I30, which in turn is connected to a coil I3I of the relay I2I' connected to a junction I32 on-the bus IN. A normally open. contact arm I33 has one side thereof connected directly to the bus I00 at a junction I34 and the other side thereof connected to a junction I35 positioned between the normally open contact I I5 of the push button 93 and the normally closed contact of the stoppush button 94. The normally open contact I33 serves to bridge the normally open contact II5 of the starting push button 93 and maintain the relay I23 energized until the control circuit associated therewith is interrupted by operation of the relay I 2I. The stop push button 64 is inserted in the circuit of coil I22 as a safety feature, whereby the apparatus may be stopped at any time during its operation.

A junction I36 on the bus I00 is connected directly to a moving arm I31 of a conventional type of step selector I40. The junction I30 is also connected to a final contact I4! of a plurality of contacts I4I--I4I associated with the arm I31 of the step selector I40. A filament transformer I42 has its primary winding I43 connected directly across the control busses I00 and IM at junctions I44 and I45 respectively. A

secondary winding I46 of the filament transformer MI is connected directly across filaments Ill-I41 of a pair of mercury vapor rectifier tubes I40I48. Each of the rectifier tubes I48-I48 is provided with a filament I41, and a pair of anodes or plates I50I50. Each of the plates l50--I50 are connected directly to one end of a resistor I5I, and all of the resistors I5I--I5I have their opposite ends connected together and to a junction I52. The junction I52 is connected to a resistor I53 connected to another resistor I54 which in turn is adjustably connected to an operating coil I55 of the step selector I40. The rectifier tubes I48-I40 and their associated resistors I5I-I5I, I53 and I 54 serve to supply the D. C. potential necessary to operate the step selec tor I40.

The other side of the coil I55 is connected to succeeding contacts I56-I56 and to a normally closed contact arm I51, the other side of which is connected to a final contact I58 of the step selector I40. A plurality of contacts I59-I53 are positioned adjacent to and horizontally aligned with the contacts I56I56. Another final contact I60 is positioned adjacent to and horizontally aligned with the final contact I50.

, The step selector I40 is provided with a movable arm I 61 connected to the arm I31, whereby both the arm I31 and the arm I6I are operated simultaneously when the coil I 55 is energized. The contact arm I 51 is also opened each time the coil I55 is energized by the D. C. current. The arm I 31 serves to successively engage the contacts I 4I I 4| while the arm I6I serves to successively bridge across a pair of contacts consisting of one contact I56 and one contact I53, and across the final contacts I58 and I60.

A junction I62 on the bus IOI is connected directly to a variable resistor I63 which in turn is connected to a junction I64 and thence to the final contact I60 of the step selector I40. The junction I64 is also connected to a condenser I65 which is connected to another condenser I66 which in turn is connected to the junction I52. The condensers I65 and IE6 serve to filter the D. C. Ipotential supplied by the rectifier tubes I48-I48 to the coil I55. The contact arm I51 of the step selector I40 is provided with a spring I61 which maintains the arm I51 in a normally closed position. A junction point I10, positioned between the junction point I 64 and the final contact I60, is connected to a normally open super sensitive switch which in turn is connected to the contacts I59--I59 of the step selector I40. The super sensitive switch 80 is actuated by the round-headed bolt 16 positioned on the ring 15 which in turn is indirectly driven by the motor I3.

A source of A. C. potential is connected to a three-pole switch I15 (Fig. 5) connected to three normally open contacts I15-I'IB of the magnetic contactor I23, which in turn are connected to the motor I 3.

The operation of the apparatus is as follows:

Assumin that the crosshead 25 is positioned at the top of the slide 26, the spliced cable 60 is looped over the grooved pulley 20 so that the splice 63 which is to be tested by the apparatus is positioned on the left hand side of the pulley 20. The cable length 62 of the spliced cable 60, which is positioned on the right hand side of the pulley 20, is placed in the cable grip 3| mounted on the cross head 25 and firmly held therein by turning the lever 45 so as to squeeze the cable 62 in the split bore provided by the inserts 36-36. The

spliced cable 60 is held in a substantially taut position, whereupon the treadle arm 5| is de- I. pressed to lift the weight 41 a substantial distance above the platform II). The cable length 62', whichis' below the splice 63, is placed in the cable grip 49 and firmly secured therein by turning its lever 45. The. treadle arm is now released, whereupon the weight 41 is carried entirely by the spliced cable 60 and serves to exert a substantial tension on the'individual welded joints within the splice63. 1

Having secured the spliced cable 60 in thecable grips 3| and 49, the connectors 3989 of the cable are inserted into the connectors 81-81 of the test set 85. The spliced cable 60 is now connected to the continuity indicating circuit (Fig. 5), whereupon the push button 92 associated therewith is actuated to close the energizing circuit of the transformer I66,-thereby causing the indicating lamps 9I-9I to glow, which fact indicates that theconductors II IIlI of the cable length 6| are now' making good electrical contact with the conductors II3-I I3 of the cable length 62;

The push button 92 is maintained in the closed position and the start push button 93 is actuated,

thereby closing the circuit to the operating coil I22 of the magnetic contactor I23 which when energized closes its control contact I 33 and its motor circuit contacts I16I16. The contact I33 provides a holding circuit for the coil I22 so that the push button 93 may be released after the contact I33 has closed. Assuming that the three-pole switch I is closed, the contacts I16-.-I16 serve to apply potential to the motor I 3, whereupon the motor is energized and reciprocates the crosshead 25 along the slide 26.

As the crosshead 25 is driven to its lower position on the slide 26, the splice 63 is drawn around the periphery of the pulley 28, and assumes a position on the right hand side of the pulley directly above the crosshead slide '26, and the weight 34 is raised to its uppermost position in the guide 33. On the return stroke of the crosshead 25, the splice 63 passes back over the periphery of the pulley 28 and assumes its normal starting position on the left hand side of the pulley, and the weight 34 returns to its lowermost position; At the same time, the roundheaded bolt 16 has made a complete revolution and actuated the operating arm 82 of the microswitch 80, thereby closing the D. C. circuit to the coil I55 of the step selector I40, whereupon the arms I31 and IN are advanced to their respective No. 1 positions. As the bolt 16 of the ring 15 passes over the operating arm 82 of the microswitch 80, the D. C. circuit to the coil I55 is opened and the arms I31 and I6I remain in their advanced position. The motor I3 continues to' reciprocate. the crosshead 25 until the bolt 16 thus actuated, the holding circuit for the coil I22 is broken whereby the relay I23 is de'energized.

The contacts I16-I 16 of the relay I23 are thereby opened and disconnect the-motor I3 from the source of potential whereupon the flexing apparatus is no longer operated. When the arm I6I bridges across the final contacts I58 and 1-60, the D. G. circuit to the coil 1 55'is maintained through the contact arm I51 and is supplied directly from 8 the junction I62 and the resistor I54. At this point the coil is energized until it opens the contact arm I51, whereupon thearms I31 and I6I advance another step. The spring I61 recloses the contact arm I51 and the coil I55 is again energized whereby the arms I31 and IBI are advanced another step. The step selector I40 con- ,tinues to operate in this manner until the arms I31 and I6I return to their normal starting posi-- tions. However, the relay I'2I remains energized through its hold-in contact I21 and another flexing operation cannot be initiated until the push button 93 is actuated so that its contact I25 is momentarily opened thereby breaking the holding circuit of the coil I3I. When the arms I31 and I6I are returned to their normal starting positions, they do not interrupt their associated control circuits while they are energized due to the fact the contact arm I51 has previously opened the D. C. circuit to the coil I55 and the contact I21 of the relay I2I is'held in a closed position maintaining the coil I3I energized even though the arm I31 has been withdrawn from its final contact I4 I.

The splice 63 of the spliced cable has now been flexed ten times due to the automatic operation of the flexing apparatus and, therefore, is ready to be removed therefrom. During the flexing operation the operator is required to hold the push button 92 in a closed position in order to determine Whether the butt-Welded joints within the splice 63 remain intact during the flexing operation, which fact is indicated by the lamps Ill-9|. In other words, should any one of the lamps 9I-9I be darkened during the flexing operation, it would indicate that one of the welded joints within the splice 63 has been broken and caused to separate during the flexing operation.

After the motor I3 has been automatically stopped by the intermittent operation of the step selector I46, the push button 92 is released and the spliced cable 60 removed from the'testing apparatus so that another spliced cable may be positioned thereon and connected to the test set as described above. The splice of the cable now positioned on the apparatus is subjected to the plurality of flexing operations like that described for the spliced cable 60.

While the above described apparatus is particularly adapted to test and flex cable splices of the type described, it is to be understood that it may be modified to test other types of cable splices and other types of cables without departing from the scope of the invention as defined in the appended claim.

What is claimed is:

In a motor driven apparatus arranged to flex a splice joining a plurality of conductors of two cables and including a testing circuit in which the individual conductors of a cable having a.

splice therein may be connected for indicating any failures in the continuity of the conductors at the splice, the improved means for automatically controlling the operation of the apparatus,

which comprises a control circuit, a motor circuit,

said control circuit including a magnetic relay for closing the motor-circuit to start the motor, manually operable means for energizing said magnetic relay and a seond magnetic relay energizable to deenergize the first-mentioned magnetic relay, a D. C. control circuit, normally open switching means for controlling the continuity of the D. C. control circuit. a step selector relay connect-ed to be energized upon each closure of 9 the D. C. control circuit, a movable arm operable by the step selector relay for energizing the second magnetic relay after said arm has been advanced a predetermined number of steps, a second movable arm operable by the step selector switch for successively connecting the step selector relay to the D. C. circuit each time the D. C. circuit is closed, a contact arm actuated when the step selector relay is energized to return the first and second movable arms to their starting position after a predetermined number of operations thereof, and means driven by the motor for intermittently actuating the switching means controlling the continuity of the D. C. circuit, whereby when the D. C. circuit is intermittently closed it intermittently energizes the step selector relay which advances the movable arms step by step until the second relay is energized and deenergizes the first-mentioned relay which interrupts the motor circuit and stops the motor.

RICHARD D. GAMBRILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 889,993 Vaughan et al June 9, 1908 999,947 Barnum Aug. 8, 1911 1,435,314 LaVercombe Nov. 14, 1922 1,436,323 Schnable et al Nov. 21, 1922 1,785,690 Bufium Dec. 16, 1930 1,853,960 Cunningham Apr. 12, 1932 1,882,815 Haegle et al Oct. 18, 1932 2,290,198 More July 21, 1942 15 2,362,690 Fichter et a1 Nov. 14, 1944 2,393,177 Longfellow Jan. 15, 1946 2,413,137 Dederick Dec. 24, 1946 FOREIGN PATENTS 20 Number Country Date 95,885 Switzerland Aug. 16, 1922 

